A modular data center packed with servers at eBay's Project Mercury facility in Phoenix, which uses an S&C medium voltage power system (Photo: eBay)
As data centers scale up, should the voltage on your power distribution scale along with it? That's the question being posed by S&C Electric Company, which has been around for over a century and is now seeing data centers become a growing portion of its business.
At a time when many data center operators are seeking greater efficiency from their power distribution, S&C says its medium voltage UPS solutions offer up a better total cost of ownership (TCO), particularly in this world of bigger data centers. This approach is finding some believers in Phoenix, where S&C equipment is supporting data centers operated by eBay and Phoenix NAP.
"For 50, 70, 150 megawatt data centers, you can’t serve it properly at 480 volts," said Troy Miller, Marketing Manager in the Power Quality Products Division at S&C Electric Company. "At medium voltage, you get the best TCO. You save space."
Moving the UPS Outdoors
S&C says its medium voltage design offers several potential advantages. It makes it easier for data centers to use the UPS system to provide backup power to an entire facility, including chillers and other mechanical infrastructure as well as the IT equipment. Because it can work outdoors, S&C's UPS and distribution switchgear also allows data center operators to move the UPS infrastructure into the equipment yard, leaving more space for rentable cabinets inside the white space.
There are some considerations and potential tradeoffs. S&C's PureWave UPS is an "offline" system, meaning the batteries are connected to the energized bus only when the system is supplying power to the load. Most conventional data center UPS systems are online systems.
Phoenix NAP is one example of a multi-tenant data center leveraging S&C to maximize its footprint. S&C provides the full backup for that location. Phoenix NAP houses its PureWave UPS outdoor in an equipment year, allowing it to maximize the data center space within.
eBay was out of room at Project Mercury. The containerized data center in Phoenix is one of the most efficient data centers ever built. eBay leveraged S&C’s solution to free up some space inside, placing power infrastructure outside.
Case Study: International Trading Company
There are also examples of enterprise implementations. A major international trading company needed a reliable power system to keep its new Tier 3 data center running smoothly. The facility’s future load of 200 MVA challenged engineers to develop a highly reliable distribution system on a limited real estate footprint.
The customer's engineering firm proposed building a 34-kV distribution system to support the data center. S&C was hired to review the design and found it wasn't compatible with the facility’s power reliability and redundancy needs. The proposed solution also would cost a truckload. S&C presented a new design that ensured reliability and redundancy while considering space constraints.
S&C proposed a compact 138-kV/13.8-kV substation that provided redundant power sources using two independent energized buses. Each bus could accommodate up to four 25-MVA transformers. It was more reliable and fit into the company’s small 150 x 350 foot lot located at one end of the site.
“In the case of this customer, we created a 100 megawatt substation expandable to 200 megawatts," said Miller. "We delivered the substation in 9 months.”
Maintenance Benefits
There’s also a potentially unforeseen advantage of moving the power distribution outside. “We worked with a lot 3-letter agencies," said Miller. " They were excited about doing the power distribution outside – maintenance people don’t need clearance.
“One of our key messages is that we understand medium voltage, we’re on the power side of the house,” said Miller. “From 2 megawatts to 16 megawatts, as you’re expanding, on medium voltage you can double capacity easily.”
The biggest trend the company is seeing is that data centers are getting bigger and bigger. “When you start talking about 30, 60 100 megawatts, and you want to do that with diesel generator backup, you have to think about how you do this in a different way," said Miller. "It doesn’t make sense at 480v. Natural gas turbines is one potential way, and there’s what we’re doing with medium volt input.”
